Device for producing code characters, for use with typewriters and similar characterprinting apparatus



March 22, 1966 s. s. v. STENUDD 3,241,648

DEVICE FOR PRODUCING CODE] CHARACTERS, FOR USE WITH TYPEWRITERS ANDSIMILAR CHARACTER PRINTING APPARATUS Filed June 9, 1.964 S Sheets-Sheetl FIGJ 'FIG .2I FlG.3 FIGA INVENTOR SVEN GUNNAR VALTER STENUDD BY WATTOR N E YS March 22, 1966 s. v, s D 3,241,648

DEVICE FOR PRODUCING CODE CHARACTERS, FOR USE WITH TYPEWRITERS ANDSIMILAR CHARACTER PRINTING APPARATUS Filed June 9, 1964 5 Sheets-Sheet 2INVENTOR SVEN GUNNAR VALTER STENUDD ATTORNEYS March 22, I966 DEVICE FORPRODUCING CODE CHARACTERS, FOR USE Filed June 9, 1964 (d) TM (h) VS 5.cs. v. STENUDD 3,241,648

WITH TYPEWRITERS AND SIMILAR CHARACTER PRINTING APPARATUS 5 Sheets-Sheet3 INVENTOR SVEN GUNNAR VALTER STENUDD ATTORNEYS United States Patent3,241,648 DEVICE FOR PRODUCING CODE CHARACTERS, FQR USE WITH TYPEWRITERSAND SIMILAR CHARACTER PRINTING APPARATUS Sven Guunar Valter Stenudd,Lidingo, Sweden, assignor to Ab Atvidabergs Industrier, Atvidabergs,Sweden Filed June 9, 1964, Ser. No. 373,707 Claims priority, applicationSweden, June 11, 1963, 6,450/ 63 Claims. (Cl. 197-1) In intergated dataprocessing procedures it is desired to produce a document readable bymeans of a machine, and at the same time to write an original document.A common example is an order routine where the order receiverconcurrently with recording the order produces a perforated tape whichthen can be utilized as a base for stock book keeping, billing, businessbook keeping, etc. in completely automatically performed operations.

For producing the document readable by machine means typewriters havepreviously in most cases been used which are coupled topunch means ofthe type similar to that used for teleprinting. The decoding of the keyfunctions is performed by means of a system of code bars which uponoperation of the keys are displaced in various manners to produce abinary code representative of the typed character. Such machines,however, are expensive and slow in operation. Another possibility is toprovide, for each key, a number of contacts corresponding to the code ofsaid key. Due to the great number of contacts, however, such anarrangement will have little reliability. This reliability may besomewhat improved by providing only one contact for each key, but insuch cases an extensive decoding network will be necessary, usuallycomposed of semiconductor diodes.

All the arrangements referred to above are hampered by an additionaldrawback. The feeding-out of a code character is due to a key operationbut there is no checking that the character has actually been printed.There may, for example, exist an obstacle in the path of the type bar.In such a case a code character will be fed out but since the operatordoes not observe any written character he will retype it and,consequently, a double feeding-out will result.

These drawbacks can be avoided by means of a device according to theinvention. With such a device the feeding-out of the code characters iseffected without any interposition of mechanic coding devices orelectric contacts. Possibly, some contact may be present for producingcode characters for such functions which have not been printed, e.g.spacing and carriage return. Further, the code character is not produceduntil the character has actually been printed.

The device according to the invention for producing code characters withtypewriters and similar kinds of character printing apparatus,comprising a plurality of type bars, the character supporting parts ofwhich during the travel towards a base move in a substantially commonpath by means of a type guide, is characterized by the fact that eachtype carrier, in association with the type supporting part, is providedwith a number of perforations arranged in a predetermined pattern, alight source and a light sensing device being positioned on oppositesides of said common path, the light sensing device comprising a numberof photo cells positioned in accordance with said pattern.

The invention will be further disclosed with reference to theaccompanying drawings, where FIG. 1 is a perspective view of the key-barand type guide of a typewriter provided with a device according to theinvention. FIG. 2 is a detail of a type bar. FIGS. 3 and 4 are differentmodifications of the code printers mounted on the key- 3,241,648Patented Mar. 22, 1966 bars. FIG. 5 shows the positional relationship ofthe perforations of the code plate and the photo cells, in the read-outposition. FIG. 6 is a logic schematic representation of the electronicunit associated with the readout device. FIGS. 7a-h show the wave formsof different signals in the electronic unit.

In FIG. 1 a type bar section in a typewriter has been given thedesignation -1. In the slots 10 thereof the type bars 2 are arrangedsuch that the top of the type bar, when actuated, passes through a typeguide 7 centering the type 3 when it strikes against the platen orroller 11. The top of the type bars are bent such that the type willdeliver characters along a vertical line when striking the platen. Thetype bar has behind its type a perforated part 5 which can either beintegral with the type bar, or be a separate plate fixed to the type barby clamping or soldering means. The perforated or punched part, i.e. thecode plate 4, has a number of perforations 5 arranged in a predeterminedpattern. On the section 1 a light source 8 is mounted for emitting abundle of parallel light rays along the platen 11. At the opposite sideof the type guide a photo cell device 9 is positioned coaxially with thelight bundle. The photo cell device consists of a number of small photocells, the operative parts of which are arranged in a patterncorresponding to the perforations in the code plate 4. When the type barduring its actuation moves against the platen the type and the codeplate will enter the light bundle from the lamp 8, and just before thestriking of the type against the platen the perforations of the codeplate will register with the corresponding photo cell 9.

The code plate provided on each type bar has a predetermined combinationof perforations, e.g. that shown in FIGS. 2 and 5, composed of theperforations Hl-H6. 'For example, H 1 may be open whereas all the otherperforations may be closed to the letter A; H1 and H2 may be open toletter B, etc.

The perforation HP is provided for adding a parity bit to the code inorder to make possible a parity check of the code character during thesubsequent processing (punching, computer operation). When odd parity isused the perforation HP should be open to the letter B but closed to A,so that the sum of the open perforations is an odd number.

The perforation HS has an auxiliary function as it is utilized forproducing a supervisory pulse for determining the instant thereading-out of the remaining perforations in the code plate is to takeplace, as described below.

The code plates may either be provided, by punching, with only theperforations desired, or they may be provided with the whole set ofperforations in accordance with the chosen configuration, for example asshown in FIGS. 2 to 5. In the latter case, those perforations thatshould not transmit a signal are obstructed by means of a plastic plugor a lump of wax. It will then be very easy to modify the code foradaption to the special purpose of the utilization of the code signal.

The location of the perforations in the code plate may obviously bevaried within wide limits. From space requirements reasons it isconvenient to arrange the perforations in a symmetrical array inaccordance with FIGS. 2 and 3. In FIG. 4 there is shown a further pos'sible positional arrangement.

FIG. 6 shows the electronic means used for producing the codecharacters. C1-C6, CP and CS are here representing the photo cellscorresponding to the perforations H1-H6, HP and HS in the code plate.The photo cells C1-C6 and CP are connected to pulse shaping gates A1-A6and AP. Each of the gates A1A6 is connected through respective or-gatesBl-B6 to an individual bistable register multivibrator D1-D6 while thegate AP is connected to a bistable multivibrator D8 through a parity bitgenerator PG and an or-gate B8.

The photo cell CS for producing the supervisory pulse is connectedthrough a pulse shaping amplifier FS, an orgate G and an inhibiting gateH to the trigger input of a monostable multivibrator TM having a pulseduration sufficient for letting the perforation HS complete its passagepast the photo cell CS during the return travel of the type after thereversal. The purpose of said multivibrator is to prevent a falsereading-out when light strikes the photo cell CS during said returntravel. The monostable multivibrator TM also triggers the monostablemultivibrator TL which, in its turn, triggers the monostablemultivibrator NP. The latter multivibrator transmits a zero-settingpulse of short duration to the registers Dl-DS while the first-mentionedcircuit feeds an enabling pulse to the gates Al-A6, AP, so that theinformation read out by the photo cells can be transferred to theregisters. The monostable multivibrator TM also operates to set thebistable multivibrators VF and VS; said multivibrators performingcertain control functions and transferring the information contained inthe registers to the data registering apparatus through the gates El-ES.For the purpose of producing code characters for the typographicalfunctions of the typewriter, e.g. the tabulator TAB, line shift NL, backspace BS, spacing MS and shift SG, which functions normally are notprinted, contacts may be provided in association with the correspondingoperation keys and be connected to a decoder KM for producing the codeand feeding it to the registers Dl-DS. As to the shift function it hasbeen assumed that the seventh bit of the code is reserved for indicatingshifts. Thus, in shift operations it will be necessary to invert theparity bit to obtain the appropriate polarity. For checking the correctreadingout of the code perforations a parity check circuit, known perse, is provided to prevent the information contained in the registersfrom being transferred to the registering apparatus if the parity checkshould disclose a non-correspondence.

The operation will now be described more in detail with reference to thepulse graphs shown in FIGS. 7a-h.

When a key-bar moves in its path towards the platen the type head willsuccessively shield the photo cells C1-C6, CP, CS from the light rays ofthe lamp 8 starting from C3 and C4 in FIG. 5. The photo cell currentwill then be reduced as shown at the time in FIG. 7a.

.At the time t1 the last cell CS is shielded (FIG. 7b).

During the further motion of the type towards the platen the whole or apart of a perforation may pass a photo cell before the code platearrives at a position in which the perforation HS registers with thecell CS. For example, the perforation HS may admit light to the cell CP.The signal then being produced is, however, prevented from reaching theregister D8 as the gate AP is disabled as long as the multivibrator TLis reset or remains in its zero-position. At the time t2 theperforations H1-H6 start to admit light to the corresponding photo cellsC1- C6, CP. In order to assure a maximum of light flow to the photocells C1-C6, CP, the perforation HS is slightly displaced with respectto the photo cell CS so that this cell will be illuminated somewhatlater than the remaining photo cells. That is because the multivibratorTM should normally be triggered before the full illumination of thephoto cell CS to ensure that the deterioration with time of the lamp orthe photo cell will not severely affect the reliability. FIG. shows thepositional relationships of the cells and the perforations as seen inthe direction towards the light source at the time t3 when theillumination of all photocells except CS is essentially at its maximumvalue.

Approximately at the time t3 the multivibrator TM is triggered by thepulse from the pulse shaping amplifier PS via the or-gate G and theinhibiting gate H. When TM is set the multivibrator TL is triggered and,in its turn, triggers the multivibrator NP. The pulse duration t3-t6 ofthe multivibrator TM is sutficient for preventing the perforation HS ofthe code plate from initiating a spurious triggering pulse to TM at thereturn of the code plate after the striking action. The multivibrator NPproduces a pulse of a very short duration setting the registers D1-D7 totheir zero-position. The multivibrator TL, being operative within theinterval t4-t3, enables the gates A1A6 so that the information obtainedfrom the photo cells can be operative to set the registers D1- D6. Theregister D7 is set by a contact of the shift key. The pulse from TL willalso enable the gate AP to pass the parity bit so that it may berecorded in the register D8, possibly after having been inverted in theparity generator PB on account of a type shift.

At the time 14 of termination of the pulse from the photo cell amplifierPS, the type has advanced still nearer to the platen and is in itsstrike position. At this instant the pulse TM is allowed to pass throughthe gate N to trigger the bistable multivibrator VF. The multivibratorVF records that a striking action has been started, andas shownbelow-the multivibrator VF is reset within a predetermined time intervalto enable the information stored in the registers Dl-DS to betransmitted to the registering apparatus.

The resetting of the multivibrator VF will be effected only when signalsare present on all input terminals of the and-gate P; this will be thecase when the multivibrator TM is set, a signal is obtained from PS, theinformation contained in the registers D1-D8 has the correct paritywhichis indicated by the parity check circuit PC-and a ready signal SH isdelivered from the registering apparatus. At this resetting a pulse isproduced which, after having been derived passes through the gate Menabled by the pulse TM, and sets the bistable multivibrator VS.Provided the registering apparatus delivers a ready signal SH theand-gate S is enabled, and a recording order OS is transmittedconcurrently with the registers D1D8 being connected to the terminalconductors Tl-TS of the registering apparatus via the andgates El-ES.

In its set condition the multivibrator VS inhibits the gate I-I so thatadditional signals from the photo cell CS cannot trigger the monostablemultivibrators TM. For example, this may occur with the pulse obtainedat the time t7 when the leading edge of the pulse leaves the typeposition so that all of the light flow will fall upon the photo cells.In case the multivibrator VS has not been set at the time t7, it is truethat TM and VP are triggered; VF, however, not having been reset at theappropriate time results in an error signal as described subsequently.The multivibrator VS is reset when the registering apparatus againdelivers a ready signal SH.

By way of example only, the amplifier F8, in accordance withconventional practice, may include a differentiating circuit and atrigger circuit to produce the pulse at time t7. Thus, if the output ofthe photo cell CS remains high for a preselected time interval, thedifferentiating circuit will reduce the input to the trigger below thethreshold value thereby producing the illustrated pulse. In the case ofthe pulses shown at times :3 and t5, the output from the photo cell CSdoes not remain high long enough to utilize the differentiating actionof the amplifier, which behaves merely as a pulse shaper.

If no recording order OS is given after the initiation of a typestriking action, this may be due to one of the following faults:

(1) The character has the wrong parity due to the registers Dl-D8 havingmissed a signal. Thus, the multi vibrator VF cannot be reset as one ofthe requirements for the and-gate P is absent. A possible reason forthis fault may be foreign material in a perforation of the code plate ora deficient photo cell.

(2) The velocity of the type is too low so that the pulse produced bythe photo cell CS during the return travel of the type will appear onlyupon the termination of the pulse TM, i.e. the time 15 occurs after t6.Also in this case one of the requirements for the gate P will be absent.This faulty operation may be due to an obstacle in the path of the typeso that it will be decelerated and thus not able to develop a sutficientforce to print a character on the paper. This control of the preventingof a recording action in the absence of a second pulse from the photocell CS within a predetermined time interval also prevents falsereading-outs due to the introduction of objects, as, for example, paperand erasing plates, in the path of the light rays.

(3) A time interval of too short a duration between two characters sothat the registering apparatus will not have completed the writing of acharacter when the next type performs its striking action. Also in thiscase one requirement for the and-gate P will be absent so that theresetting of the multivibrator VF will be impossible. This type ofdefective function may be due to a faulty registering apparatus.

If the multivibrator VF has not been reset before the resetting of themultivibrator TM, an error indication will result as a consequence ofthe gate K allowing a stop signal OP to pass which in the first placeactuates a magnet (not shown) which locks the keys of the typewriter,and in the second place disables the gate H thus preventing a triggeringof the multivibrator TM. For continuing the Writing the multivibrator VFhas to be reset manually either by means of a push button RVF or byoperating the back spacer BS of the type writer; after that it will bepossible to resume the writing.

Whenever one of the keys associated with the typographic functions TAB,NL, BS, MS is operated a signal VK will result which passes through thegates G and H and triggers the multivibrators TM, TL and NP. The signalsreceived from the code matrix KM are instantly recorded in the registersE1438, and if the parity condition is satisfied and a ready signal SH isdelivered the multivibrator VF is immediately reset, and a recordingorder is issued. As stated above, a wrong parity or the absence of aready signal will result in an error indication.

Preferably the invention can be used with pulse controlled characterprinting apparatus, particularly with typewriters, for checking that thecorrect character has actually been printed. With the conventional pulsecontrolled typewriters which, for example, are used for writingcharacters delivered by computers, the movement of the type-bars isreleased by magnetic means; however, there is no checking that thecorrect type-bar actually strikes the paper. By comparing the controlsignal with the information received from a device it will be possibleto obtain a confirmation of the fact that the correct character hasactually been printed. Should the comparison indicate the printing of awrong character retyping takes place or an error signal is delivered.

What I claim is:

1. A device for producing coded characters in typewriters and the like,comprising at least one movable mask having light permeable openingscorresponding to a coded character, a light source, a plurality ofphotocells for reading the code represented by the openings of said maskwhen it is interposed between said light source and photocells, saidopenings have closed contours and permitting all of said photocells tobe illuminated when said mask is in a first position, the illuminationof at least one photocell being temporarily intercepted by the maskduring movement of said mask from said first position to said interposedposition, means utilizing the output of said one photocell when saidmask is in the interposed posi tion for initiating read-out of saidcode, storage means, and gate means connected between said photocellsand said storage means, said utilizing means enabling said gating meansto pass signals from said photocells to said storage means only whensaid openings are positioned in a predetermined manner with respect tosaid photocells.

2. A device according to claim 1, wherein said typewriter comprises aplurality of type bars containing respective type characters thereon,there being an individual mask associated with each type bar, each ofsaid masks being located immediately behind the character of itsassociated type bar, at least one of the openings in said masks causingsaid one photocell to be illuminated both before and after the type barhas caused the type character thereon to be printed.

3. Apparatus for use with a typewriter or the like wherein a movabletype bar having thereon at least one character is adapted to be moved ina forward direction from an initial position to reproduce such characterand wherein means are provided to return said type bar to its initialposition, comprising a coded optical mask secured to said bar, a lightsource, photosensitive means situated in the path of said light sourceand responsive to the interposition of said mask in said path forproducing coded signals representative of the character on theassociated type bar, each of said masks being shaped to cause saidphotosensitive means to produce discrete electrical signals during theforward and return movements of the associated bar, means fortransmitting said coded signals only when the delay between saiddiscrete signals does not exceed a predetermined time interval, storagemeans, and means responsive to the occurrence of said first discreteelectrical signal for coupling said coded signals to said storage means,said transmitting means being operative to cause readout of theinformation in said storage means.

4. Apparatus according to claim 3, including error checking means, andmeans responsive to said error checking means for inhibiting operationof said transmitting means in the event such coded signals contain anerror.

5. Apparatus according to claim 3, including error indicating means forindicating when the delay between said discrete signals exceeds saidpredetermined time interval.

References Cited by the Examiner UNITED STATES PATENTS 2,350,893 6/1944Hofgaard 1971 2,408,754 10/1946 Bush 1975 X 3,017,978 1/1962 Schulz19717 3,032,163 5/1962 Flieg 1971.5

3,080,110 3/1963 Plaisance 234-l08 X 3,096,016 7/1963 Flieg 234108ROBERT E. PULFREY, Primary Examiner.

EDGAR S. BURR, Assistant Examiner.

1. A DEVICE FOR PRODUCING CODED CHARACTERS IN TYPEWRITERS AND THE LIKE,COMPRISING AT LEAST ONE MOVABLE MASK HAVING LIGHT PERMEABLE OPENINGSCORRESPONDING TO A CODED CHARACTER, A LIGHT SOURCE, A PLURALITY OFPHOTOCELLS FOR READING THE CODE REPRESENTED BY THE OPENINGS OF SAID MASKWHEN IT IS INTERPOSED BETWEEN SAID LIGHT SOURCE AND PHOTOCELLS, SAIDOPENINGS HAVE CLOSED CONTROURS AND PERMITTING ALL OF SAID PHOTOCELLS TOBE ILLUMINATED WHEN SAID MASK IS IN A FIRST POSITION, THE ILLUMINATIONOF AT LEAST ONE PHOTOCELL BEING TEMPORARILY INTERCEPTED BY THE MASKDURING MOVEMENT OF SAID MASK FROM SAID FIRST POSITION TO SAID INTERPOSEDPOSITION, MEANS UTILIZING THE OUTPUT OF SAID ONE PHOTOCELL WHEN SAIDMASK IS IN THE INTERPOSED POSITION FOR INITIATING READ-OUT OF SAID CODE,STORAGE MEANS, AND GATE MEANS CONNECTED BETWEEN SAID PHOTOCELLS AND SAIDSTORAGE MEANS, SAID UTILIZING MEANS ENABLING SAID GATING MEANS TO PASSSIGNALS FROM SAID PHOTOCELLS TO SAID STORAGE MEANS ONLY WHEN SAIDOPENINGS ARE POSITIONED IN A PREDETERMINED MANNER WITH RESPECT TO SAIDPHOTOCELLS.